I. Field of the Invention
This invention relates generally to large industrial vehicles and more particularly to a hydraulically ladder for facilitating the ability of a machine operator to reach the operator's station.
II. Discussion of the Prior Art
Large work vehicles used in earth moving and mining operations and other construction industries, such as dozers, drag lines, excavators, forest machines, mining shovels, trucks for hauling ore, etc, are characterized by having an operator's station or cab that is elevated several feet, sometimes as much as 20 feet, above ground level. Such equipment often includes one or more fixed ladders for allowing a worker to more readily mount the equipment. Power lifts have also been devised, one such lift being shown in the Rivinius U.S. Pat. No. 4,217,971. This patent shows a cage or basket at one end of a pair of hydraulically actuated arms that are designed to lift and also rotate the cage carrying the operator from ground level to a location closely adjacent a deck or walkway located immediately below the operator's station. From the deck, the operator may easily enter his or her work station.
Similarly, the Hemisen U.S. Pat. No. 3,656,578 shows a work vehicle of the type described on which a ladder is pivotally mounted such that it can be manually swung from a vertical orientation used when mounting the vehicle to a horizontal, stowed position that forms a guardrail that blocks exit of a worker from the work station. For a ladder built to withstand the forces and environment encountered in mining and other earth-moving applications, it is somewhat of a challenge to move the ladder from its vertical use position to its horizontal stowed position.
It is therefore an object of this invention to provide a hydraulically actuated ladder capable of deploying the ladder from a stowed position lying underneath and parallel to the vehicle's horizontal deck to a vertical use position where the ladder's bottom end is adjacent the ground and its upper end rests against the outer edge of the vehicle's deck. In the stowed position, it is completely out of the way and not an obstacle to a worker's ability to traverse the deck.